Layers of Protection Analysis Using Possibility Theory

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Nouara Ouazraoui 1,* Rachid Nait-Said 1 Mouloud Bourareche 1 Ilyes Sellami 2

1. Laboratory of Research in Industrial Prevention (LRIP), Health and Occupational Safety Institute, Safety Department, University of Batna, Med El-Hadi Boukhlouf Street, Batna 05000, Algeria

2. Entreprise Nationale des Travaux aux Puits (ENTP Company), B.P. 206, Hassi-Messaoud, Algeria

* Corresponding author.


Received: 3 Jan. 2012 / Revised: 29 May 2012 / Accepted: 1 Sep. 2012 / Published: 8 Dec. 2012

Index Terms

LOPA, Uncertainty, Possibility Theory, Risk Reduction


An important issue faced by risk analysts is how to deal with uncertainties associated with accident scenarios. In industry, one often uses single values de-rived from historical data or literature to estimate events probability or their frequency. However, both dynamic environments of systems and the need to consider rare component failures may make unrealistic this kind of data. In this paper, uncertainty encountered in Layers Of Protection Analysis (LOPA) is considered in the framework of possibility theory. Data provided by reliability databases and/or experts judgments are represented by fuzzy quantities (possibilities). The fuzzy outcome frequency is calculated by extended multiplication using α-cuts method. The fuzzy outcome is compared to a scenario risk tolerance criteria and the required reduction is obtained by resolving a possibilistic decision-making problem under necessity constraint. In order to validate the proposed model, a case study concerning the protection layers of an operational heater is carried out.

Cite This Paper

Nouara Ouazraoui, Rachid Nait-Said, Mouloud Bourareche, Ilyes Sellami, "Layers of Protection Analysis Using Possibility Theory", International Journal of Intelligent Systems and Applications(IJISA), vol.5, no.1, pp.16-29, 2013.DOI:10.5815/ijisa.2013.01.02


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